Nitride-inclusion characterization in lightweight steel and reprecipitation behavior of AlN during heat treatment: effect of Al content
Jin-long Wang1,2, Sheng-qiang Song1,2, Zheng-liang Xue1,2, Dai Tang3, Gang Tong4, Dong-ming Liu1,2
1 The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China 2 Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China 3 Department of Materials Science & Engineering, Center for Iron and Steelmaking Research, Carnegie Mellon University, Pittsburgh, PA 15213, USA 4 Wuhan Iron and Steel Company Limited, Wuhan 430081, Hubei, China
Nitride-inclusion characterization in lightweight steel and reprecipitation behavior of AlN during heat treatment: effect of Al content
Jin-long Wang1,2, Sheng-qiang Song1,2, Zheng-liang Xue1,2, Dai Tang3, Gang Tong4, Dong-ming Liu1,2
1 The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China 2 Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China 3 Department of Materials Science & Engineering, Center for Iron and Steelmaking Research, Carnegie Mellon University, Pittsburgh, PA 15213, USA 4 Wuhan Iron and Steel Company Limited, Wuhan 430081, Hubei, China
摘要 The composition, morphology, size, and number of inclusions in Fe–22Mn–xAl–0.7C (x = 0.5%, 5.2%, and 10.5%) lightweight steels after smelting and heat treatment experiments are characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy from both 2D and 3D perspectives. The inclusions are classified into eight categories according to chemistry and morphology. For the steel sample with a low Al content (0.5%), the inclusions are MnS, AlN– MnS, and Al2O3–MnS, among which Al2O3–MnS is the primary type. With the increase in Al content in the steel sample (to 5.2%), the populations of AlN and AlN–MnS inclusions of 1–3 lm in diameter increase. A further increase in Al content (to 10.5%) leads to a significant decrease in the amount of AlN inclusions of 1–3 lm in diameter, and an increase in the amount of AlN–MnS inclusions. The precipitation behavior during the phase transformation is also studied by FactSage 8.0 thermodynamic software, and a precipitation mechanism is proposed based on the calculation results. During the heat treatment, AlN inclusions re-precipitate out, due to the interactions between Al and dissolved N in the steel matrix. However, AlN inclusions cannot grow large because of unfavorable kinetic conditions. The re-precipitation phenomenon of AlN is predominant under low Al and high N conditions but not at high Al cases.
Abstract：The composition, morphology, size, and number of inclusions in Fe–22Mn–xAl–0.7C (x = 0.5%, 5.2%, and 10.5%) lightweight steels after smelting and heat treatment experiments are characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy from both 2D and 3D perspectives. The inclusions are classified into eight categories according to chemistry and morphology. For the steel sample with a low Al content (0.5%), the inclusions are MnS, AlN– MnS, and Al2O3–MnS, among which Al2O3–MnS is the primary type. With the increase in Al content in the steel sample (to 5.2%), the populations of AlN and AlN–MnS inclusions of 1–3 lm in diameter increase. A further increase in Al content (to 10.5%) leads to a significant decrease in the amount of AlN inclusions of 1–3 lm in diameter, and an increase in the amount of AlN–MnS inclusions. The precipitation behavior during the phase transformation is also studied by FactSage 8.0 thermodynamic software, and a precipitation mechanism is proposed based on the calculation results. During the heat treatment, AlN inclusions re-precipitate out, due to the interactions between Al and dissolved N in the steel matrix. However, AlN inclusions cannot grow large because of unfavorable kinetic conditions. The re-precipitation phenomenon of AlN is predominant under low Al and high N conditions but not at high Al cases.
Jin-long Wang,Sheng-qiang Song,Zheng-liang Xue, et al. Nitride-inclusion characterization in lightweight steel and reprecipitation behavior of AlN during heat treatment: effect of Al content[J]. Journal of Iron and Steel Research International, 2023, 30(02): 350-362.
2023, Vol. 30 
